Reaction of phosgene and cyanogen chloride

ABSTRACT

Phosgene and cyanogen chloride are reacted under pressure in the liquid phase over an activated charcoal catalyst at 100* to 250* C to produce a mixture of chlorocarbonylisocyanide and carbonylbis-(N-isocyanide dichloride).

Jan. 7, 1969 Germany ..P 1 9 542.6

United States Patent 1 3,699,162 Hagemann 51 *Oct. 17, 1972 [54]REACTION OF PHOSGENE AND [52] US. Cl. ..2t/544 C, 260/553 R CYANOGENCHLORIDE [51] Int. Cl. ..C07c 51/58 [72] Inventor: Hermann Hagemann,Cologne, Gen [58] Field of Search ..260/544 C, 55 3 R man y [56]References Cited [73] Asslgnee: Farbenfabriken Bayer Aktiengesellschaft,Leverkusen, Germany UNITED STATES PATENTS 1 Notice: The portion of theterm of this 3,600,439 8/1971 I-lagemann ..260/553 R patent subsequentto Aug. 17, 1988, has been cla med- Primary Examiner-Lorraine A.Weinberger 2 Filed: Dec. 5 Assistant ExaminerRichard Attorney-Burgess,Dinklage & Sprung {21] Appl. No.: 884,895

Related U.S. Application Data [57] ABSTRACT [63] Continuation-impart ofSer. No. 731,284, May Phosgene, and (fyaflogen chloride are reactedunder 1968 Pat. 3 600 pressure m the liquid phase over an activatedcharcoal catalyst at to 250 C to produce a mixture of 0 ForeignApplication Priority Data chlorocarbonylisocyanide andcarbonyl-bis-(N-isocyanide dichloride).

3 Claims, 1 Drawing Figure PATENT ED N 17 1972 3.6 99, 162

INVENTOR.

HERMAN N HA GEMANIQ BY a M47! .9;

REACTION OF PHOSGENE AND CYANOGEN CHLORIDE RELATED APPLICATION Thisapplication is a continuation-in-part of Process for the Preparation ofa Mixture of N-Chlorocarbonyl- Isocyanide Dichloride andCarbonyl-bis-(N-lsocyanide Dichloride), and the Corresponding ThioCompounds, Ser. No. 731,284, filed May 22, 1968, now US. Pat. No.3,600,439.

PREAMBLE Certain highly activated acyl chlorides are capable ofundergoing addition with cyanogen chloride at temperatures of only 50Cand excess atmospheres without the use of a catalyst to formacylisocyanide dichlorides, but these acylisocyanide dichlorides are Toincrease the proportion of the compound (I), phosgene is used in thereaction in at leaststoichiometric quantity and preferably in excess, a2 to and preferably 3 to 5 times molar excess being generally employed.In order to increase the proportion of the compound (II) formed in thereaction, cyanogen chloride is used in'excess in analogous manner.lt'may be advantageous, especially in the latter case, to carry out thereaction in the. presence of one of the abovesubject to decompositionevenat room temperature under normal pressure and revert to the startingcompounds. At elevated temperatures, this equilibrium shifts completelyin favor of the I decomposition products due to trimerisation ofcyanogen chloride.

N.-chlorocarbonylisocyanide dichloride can be obtained along withcarbonyl'-bis-(N-isocyanide dichloride) if cyanogen chloride is reactedin the absence of Lewis acids with a compound of the formula:

mentioned inert organic solvents.

THIS INVENTION coal arranged in a fixed bed, the flow rate being from 1of 5 to 100 atmospheres and a temperature of 100 to 300C in the presenceof activated charcoal, the isocyanide dichlorides formed being removedby distillation. An inert solvent and/or an inert gas can be present ifdesired.

The solvents which may optionally be employed for the process arechlorinated hydrocarbons such as methylene chloride, chloroform, carbontetrachloride, chlorobenzene and dichlorobenzene and alsohexachloroethane. If the process is carried out in the presence of aninert gas, it is to be understood that this gas may be carbon dioxideor, in particular, nitrogen. The usual activated charcoals of commercecan be used for the process of the invention. Examples include, interalia, the kinds of active charcoal mentioned in Ullmanns Enzyklopadieder Technischen Chemie, 3rd Edition, and by Kirk Othmer.

The compounds obtainable by the above process correspond to the generalformula:

Cl g

in which Y represents chlorine (compound (I)) or the radicalz (compound(II)).

to 5 parts by volume of theliquid mixture of cyanogen chloride andphosgene under pressure for every part by volume of active charcoal perhour. The isocyanide dichlorides formed are removed from the reactionproduct as by distillation and the cyanogen chloride and phosgenerecovered are returned to the process.

The process is carried out in the temperature range of to 250 C, inparticular, to 180C. A pressure of 5 to I00 and, in particular, 47 to 75'atmospheres is maintainedin the reactor. The reactor can be a fixed bedreactor or a fluidized bed reactor. The process has the advantage thatit can be carried out without solvents. The catalyst can be pretreatedby passing an inert gas such as carbon dioxide or nitrogen at thereaction temperature over the catalyst in the reactor. The activecharcoal used may be any of the usual active charcoals of commerce ingranulated form or, if the reactor is constructed as a fluidized bed, inpowder form. v

The process according to the invention has the advantage that itproduces N-chlorocarbonylisocyanide dichlorides in a high yield and witha high selectivity and high conversion of the cyanogen chloride.Conversion and yield are surprisingly substantially higher in thecontinuous process according to this invention than in the discontinuousprocess. Another very surprising feature is that, in the processaccording to this invention, the expected trimerisation of cyanogenchloride to cyanuric chloride can be observed onlyto a very slightextent. Even after the process has been in operation for long periods,the proportion of cyanuric chloride in the reaction mixture stillremains surprisingly low. One obtains either a larger amount ofchlorocarbonyl isocyanide dichloride or a larger amount ofcarbonyl-bis-(N-isocyanide dichloride) in the process according towhich, of the two starting components, cyanogen chloride or phosgene, isused in excess.

The new types of compounds obtainable by the process according to theinvention can be used in the same way for further reactions as hasalready been described for the known isocyanide dichlorides.Furthermore, they may be used for the production of synthetic resinauxiliary products, plant protectionv agents or material protectionagents. They may also be used directly as plant protection agents or,material protection agents.

DRAWING The drawing is a schematic illustration of the process describedin the Example.

EXAMPLE One partby volume of granulated active charcoal is sure israised to 10 atmospheres. Phosgene is now fedv from a storage vessel 1into the reactor 15 through an atomizer plate in the bottom plate 11 ofthe reactor via a pump 10 and a calibrating device 5. Cyanogen chlorideis introduced from a storage vessel 14 by a pump 12 via a dosing device13. At the same time, the temperature, which is controlled by aninternal thermometer 16 in the reactor, is maintained at 150C. The

pressure is allowed to rise to 55 atmospheres. At 55 .at-

mospheres, the pressurized gas is released into the cooler 8 by means ofan automatically controlled valve arrangement 17, 18. The cooler 8 is sodesigned that it cools the reactionproduct to a temperature range offrom 50 to 70C. The reaction reaction product enters a container 7 whichis maintained at 65C by external heating means. Phosgene is distilledoff through a I column 23 equipped with a cooler and a reflux divider21, and enters a container 3 via a cooler 4 which, like the cooler 20,is cooled with brine at 20C. The crude product can be removeddiscontinuously or continuously from the container 7 by a siphon 6.Permanent gases, e.g. from the preparation of the catalyst,

can be removed from the cooler 20 at 19. The con- 7 tainer 3 can bereplenished with phosgene from the storage container 1 as required. Thephosgene returns to the reaction cycle from the container 3.

1.485 parts by weight of phosgene and 183 parts of cyanogen chloride arefed into the reactor 15 per hour. After a period of operation of 12.6hours, 5,331 parts of chlorocarbonyl isocyanide dichloride (i.e. 89weight percent of the theoretical), 492 parts by weight ofcarbonyl-bis-(N-isocyanide dichloride) (i.e. 5.9 weight percent of thetheoretical) and 120 parts of cyanuric chloride (i.e. 5.2 weight percentof the theoretical) are obtained. Conversion of cyanogen chloride is 97weight percent after about 100 hours. Unreacted cyanogen chloride can bereturned into circulation via the container 3 together with phosgene, sothat the proportion of fresh cyanogen chloride to be added via the pump12, can be reduced.

Conversion into the corresponding isocyanate is carried out as follows:

229.5 g (1.43 mol) of N-chlorocarbonylisocyanide dichloride areintroduced into the reaction vessel and 137.5 g (1.43 mol) ofmethylsulphonic acid are added dropwise at 20C at such a rate that thereaction tempei'ature rises to 50C. Thereafter hydrogen chloride whichis l zound in t e forrno carbamic ecid chlgride is driven 0 over a coumn in t e course 0 about hours while the sump temperatureis slowlyraised, and the N- chlorocarbonyl isocyanate remaining behind isseparated from methyl sulphochloride by distillation. 106 g ofthetheoretical) of N-chlorocarbonyl isocyanate of b.p. 64C/ 760 mm Hg areobtained.

Iclaim:

1. In a continuous process for the preparation of N-chlorocarbonyl-isocyanide dichloride and carbonylbis-(N-isocyanidedichloride) by reacting cyanogen chloride and phosgene with theexclusion of Lewis acidsover active charcoal at an elevated pressure andtemperature; the improvement whichv comprises passing in liquid phase amixture of cyanogen chloride and phosgene at a temperature of from to250C over active charcoal arranged as a fixed bed and a flow rate beingfrom 1 to 5 parts by volume of the liquid mixture of cyanogen chlorideand phosgene per part by weight of active charcoal per hour; removingthe isocyanide dichlorides thus formed and unreacted feed from theproduct reaction mixture; and returning unreacted cyanogen chloride andphosgene thus recovered to the process.

2. The process of claim 1 wherein an inert gas is added to the reactionmixture.

3. The process of claim 1 wherein the ratio of isocyanide dichlorides insaid product reaction mixture is controlled by adjusting the ratio ofsaid phosgene and cyanogen chloride in the feed.

, a Farben 1M UM'RED STATES IA'IEN'I OI' FKJE CER'HFICA'EE OF ORRECTlN3,699,162 I Dated October 17, 1972 v Patent No.

HERMANN. HAGEMANN Inventor(s) It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Cover page, under the heading "Foreign Application Priority Date" insert--Aug. 30, 1967 Germany H. F 53 353--; colum 3, line 20, "reactor 15"should be --reactor 9'; column 3, line 26, after "mometer" insert--15,-column 3, line 32, cancel "reaction" (2nd occurrence); column 3,line 45, after "183 parts" insert --by weight; column 3, line 47, after"5,331 parts" insert -by weight--; column 3, line 48, cancel "weight";column 4, line 2, cancel "weight"; column 4, line 4, cancel "weight";column 4, line 5, cancel "weight"; column 4, line 3, after "120 parts"insert --by weight"; column 3, line 36, after "container 3" insert"having a vent line 2 by way of valve 22-- Signed and sealed this 2 +thday of April "1973.

(SEAL) Attest:

EDWARD M. FLETCHER, JR. 4 ROBERT GOTT'SCHALKHW Attesting OfficerCommissioner of Patents

2. The process of claim 1 wherein an inert gas is added to the reactionmixture.
 3. The process of claim 1 wherein the ratio of isocyanidedichlorides in said product reaction mixture is controlled by adjustingthe ratio of said phosgene and cyanogen chloride in the feed.